Summary of Expression Types¶

Expression	Arithmetic meaning
1 + 2	Addition, the result is 3
3 * 4	Multiplication, the result is 12
1 / 3	Integer division, the result is 0 in older Python environments, but 0.333333333333 in Python 3
2.0 / 4.0	Division, the result is 0.5, since you are using decimal numbers in the calculation
1 // 3	Floor division, the result is 0 in Python 3
2 % 3	Modulo (remainder), the result is 2
-1	Negation, the result is -1

3 / 4

0
If the two values are both integers (whole numbers) you will normally get an integer (whole number) result in older Python environments. But, this book is using Python 3 so you get a decimal result.
1
This would be correct if the result was rounded up before the values after the decimal point were thrown away, but it does not do this.
0.75
While this isn't the what older Pyton development environments would return, in this book we are using Python 3 so it returns a decimal result.
0.25
This would be correct if it was 1 / 4, 1.0 / 4, or 1 / 4.0

18 % 5

0
This would be correct if it was 18 % 2, but what is the remainder of 18 divided by 5?
1
This would be correct if it was 18 % 17, since 17 goes into 18 one time and the remainder is 18 - 17 = 1.
2
What is the highest multiple of 5 that is less than or equal to 18? The remainder is 18 - that number.
3
The reminder is 3 since 5 goes into 18 three times (15) and 18 - 15 = 3.

2 % 6

0
This would be correct if it was 6 % 2.
1
This would be correct if it was some odd number divided by 2, but it is not.
2
6 goes into 2 zero times with 2 left over.
6
If you have a smaller number divided by a larger number the remainder is always the smaller number.